Search function anomaly with 2 o 3 numbers

i have an OmekaS Platform that has a strange behaviour in search funtion:

If i use search with “xx yy” it doesn’t found any items (even if there are in the system, for example - “af 95”.
If I use it with “xx yyy” it finds it correctly (ex. “af 100”).

How is it possible? Is there something i have to config?

The main search box uses MySQL’s fulltext search feature, which has a limitation on how many characters: by default, anything under 3 characters long is just completely ignored in a search.

You can change this setting, but it requires setting a configuration option for the MySQL server itself (in this case innodb_ft_min_token_size) and rebuilding the index.

The item advanced search’s “search by property” doesn’t have this restriction either.